VL53L1X ROI (FOV) adjustment question

[JKim.42]

Hi team,

I want to detect an moving object using the VL53L1X sensor.

However, there is a problem with the installation angle of the sensor, and we arr looking for a solution.

As shown in the above figure, there is interference from a fixed object between the sensor and the moving object in environment installed at angle of about 60 degree instead 90 degree. But, I want to detect only moving objects, not these fixed objects.

At this time, we ask whether the interference of fixed objects can be avoided by moving the FOV from the default 16x16 ROI & Center 199 to the 16x7 ROI & Center 60 as shown figure. Or, is there another solution?

Also, in ideal case, when the linear distance (D) between the sensor and object is 300mm, and the actual measurement distance (E) will be 600mm. However, since the installation angle is not a right angle, the actual measurement distance is expected to be shorter or longer than this from the sensor's point of view. But, if only a certain value is constantly measured without bouncing, i expected that it will be possible to detect.

It's a situation where can't change current installation, so we need to find a solution in current condition, please help.

Best Regards,

Jiung

[John E KVAM · Accepted solution]

Interesting questions.

You should be able to avoid your fixed object by changing the FoV. But reducing the FoV will limit the max range of the sensor. And you might find your object is so reflective that it's hard to avoid.

(Painting the fixed object a flat black can help - if possible.)

The VL53L1CB is capable of detecting multiple objects. But the difficulty is that they need to be quite a distance from each other (80cm) or they blur together.

If your targets are well known you could create a table of sensor result vs known positions.

The sensor range would not be a distance but an index into your table. But this only works if your targets are known.

The VL53L5 is a more expensive sensor, but it has an 8x8 grid of zones in a 45 degree field of view. With this you will see your fixed object in some zones, and your moving object in other zones.

I think that would be the best solution.

[JKim.42]

Unfortunately it is not possible to change the current sensor. Therefore, first, let's implement it in a way of defining a table-based object. Thank you for answer.

Regards, Jiung.

[John E KVAM]

I have another possible for you. ST just released the datasheet for the VL53L4CD and CX.

These sensors have a field of view of 18 degrees. So if the object you want to avoid is more than 9 degrees off center, you might just miss it.

the L4 is pin compatible to the L1 you have - although it's less tall.

and the software you have will work on it as well.

Parts should be available Mid Feb and all the distributors.

(The UltraLightDriver software is the same too.)

• john